Separated pupil optical systems for virtual and augmented reality and methods for displaying images using same

ABSTRACT

A method of operating an AR system to display an image viewable by a user&#39;s eyes includes tracking, by an eye-tracking subsystem, a position of the user&#39;s eyes and determining, based on the position, a focus depth of the user&#39;s eyes. The method also includes selecting, from a plurality of light-guiding optical elements, a subset of light-guiding optical elements configured to focus light at a depth plane corresponding to the focus depth of the user&#39;s eyes, producing a plurality of light beams using a subset of sub-light sources of a plurality of sub-light sources, the subset of sub-light sources being configured to illuminate the subset of light-guiding optical elements, and imaging the plurality of light beams through an imaging system and onto the subset of light-guiding optical elements such that the image is generated at the depth plane corresponding to the focus depth of the user&#39;s eyes.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/882,011, filed on May 22, 2020, entitled “SEPARATED PUPIL OPTICALSYSTEMS FOR VIRTUAL AND AUGMENTED REALITY AND METHODS FOR DISPLAYINGIMAGES USING SAME,” which is a continuation of U.S. patent applicationSer. No. 15/146,296, filed on May 4, 2016, U.S. Pat. No. 11,402,629,issued on Aug. 2, 2022, entitled “SEPARATED PUPIL OPTICAL SYSTEMS FORVIRTUAL AND AUGMENTED REALITY AND METHODS FOR DISPLAYING IMAGES USINGSAME,” which claims priority to U.S. Provisional Application No.62/156,809 filed on May 4, 2015 entitled “SEPARATED PUPIL OPTICALSYSTEMS FOR VIRTUAL AND AUGMENTED REALITY AND METHODS FOR DISPLAYINGIMAGES USING SAME.” The contents of the aforementioned patentapplications are hereby incorporated by reference in their entirety forall purposes.

This application is related to U.S. Prov. Patent Application Ser. No.61/909,774 filed on Nov. 27, 2013 entitled “VIRTUAL AND AUGMENTEDREALITY SYSTEMS AND METHODS,” U.S. Utility patent application Ser. No.14/555,585 filed on Nov. 27, 2014 entitled “VIRTUAL AND AUGMENTEDREALITY SYSTEMS AND METHODS,” U.S. Prov. Patent Application Ser. No.62/005,807 filed on May 30, 2014 entitled “METHODS AND SYSTEMS FORVIRTUAL AND AUGMENTED REALITY,” U.S. Utility patent application Ser. No.14/726,424 filed on May 29, 2015 entitled “METHODS AND SYSTEMS FORGENERATING VIRTUAL CONTENT DISPLAY WITH A VIRTUAL OR AUGMENTED REALITYAPPARATUS,” U.S. Prov. Patent 30017.00 and entitled “METHODS AND SYSTEMFOR CREATING FOCAL PLANES IN VIRTUAL AND AUGMENTED REALITY,” U.S.Utility patent application Ser. No. 14/726,429 filed on May 29, 2015entitled “METHODS AND SYSTEM FOR CREATING FOCAL PLANES IN VIRTUAL ANDAUGMENTED REALITY,” U.S. Prov. Patent Application Ser. No. 62/005,865filed on May 30, 2014 entitled “METHODS AND SYSTEMS FOR DISPLAYINGSTEREOSCOPY WITH A FREEFORM OPTICAL SYSTEM WITH ADDRESSABLE FOCUS FORVIRTUAL AND AUGMENTED REALITY,” and U.S.

Utility patent application Ser. No. 14/726,396 filed on May 29, 2015entitled “METHODS AND SYSTEMS FOR DISPLAYING STEREOSCOPY WITH A FREEFORMOPTICAL SYSTEM WITH ADDRESSABLE FOCUS FOR VIRTUAL AND AUGMENTEDREALITY.” The contents of the aforementioned patent applications arehereby expressly and fully incorporated by reference in their entirety,as though set forth in full.

BACKGROUND OF THE INVENTION

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” (collectively referred to as “mixed reality”) experiences,wherein digitally reproduced images or portions thereof are presented toa user in a manner wherein they seem to be, or may be perceived as,real. A virtual reality, or “VR”, scenario typically involvespresentation of digital or virtual image information withouttransparency to other actual real-world visual input; an augmentedreality, or “AR”, scenario typically involves presentation of digital orvirtual image information as an augmentation to visualization of theactual world around the user. Accordingly, AR scenarios involvepresentation of digital or virtual image information with at leastpartial transparency to other actual real-world visual input. The humanvisual perception system is very complex, and producing an AR or VRtechnology that facilitates a comfortable, natural-feeling, richpresentation of virtual image elements amongst other virtual orreal-world imagery elements is challenging.

The visualization center of the brain gains valuable perceptioninformation from the motion of both eyes and components thereof relativeto each other. Vergence movements (i.e., rolling movements of the pupilstoward or away from each other to converge the lines of sight of theeyes to fixate upon an object) of the two eyes relative to each otherare closely associated with focusing (or “accommodation”) of the lensesof the eyes. Under normal conditions, changing the focus of the lensesof the eyes, or accommodating the eyes, to focus upon an object at adifferent distance will automatically cause a matching change invergence to the same distance, under a relationship known as the“accommodation-vergence reflex.” Likewise, a change in vergence willtrigger a matching change in accommodation, under normal conditions.Working against this reflex, as do most conventional stereoscopic AR orVR configurations, is known to produce eye fatigue, headaches, or otherforms of discomfort in users.

Stereoscopic wearable glasses generally feature two displays for theleft and right eyes that are configured to display images with slightlydifferent element presentation such that a three-dimensional perspectiveis perceived by the human visual system. Such configurations have beenfound to be uncomfortable for many users due to a mismatch betweenvergence and accommodation (“vergence-accommodation conflict”) whichmust be overcome to perceive the images in three dimensions. Indeed,some users are not able to tolerate stereoscopic configurations. Theselimitations apply to both AR and VR systems. Accordingly, mostconventional AR and VR systems are not optimally suited for presenting arich, binocular, three-dimensional experience in a manner that will becomfortable and maximally useful to the user, in part because priorsystems fail to address some of the fundamental aspects of the humanperception system, including the vergence-accommodation conflict.

AR and/or VR systems must also be capable of displaying virtual digitalcontent at various perceived positions and distances relative to theuser. The design of AR and/or VR systems also presents numerous otherchallenges, including the speed of the system in delivering virtualdigital content, quality of virtual digital content, eye relief of theuser (addressing the vergence-accommodation conflict), size andportability of the system, and other system and optical challenges.

One possible approach to address these problems (including thevergence-accommodation conflict) is to project images at multiple depthplanes. To implement this type of system, one approach is to use a largenumber of optical elements (e.g., light sources, prisms, gratings,filters, scan-optics, beam-splitters, mirrors, half-mirrors, shutters,eye pieces, etc.) to project images at a sufficiently large number(e.g., six) of depth planes. The problem with this approach is thatusing a large number of components in this manner necessarily requires alarger form factor than is desirable, and limits the degree to which thesystem size can be reduced. The large number of optical elements inthese systems also results in a longer optical path, over which thelight and the information contained therein can be degraded. Thesedesign issues result in cumbersome systems which are also powerintensive. The systems and methods described herein are configured toaddress these challenges.

SUMMARY OF THE INVENTION

In one embodiment directed to an imaging system, the system includes alight source configured to produce a plurality of spatially separatedlight beams. The system also includes an injection optical systemconfigured to modify the plurality of beams, such that respective pupilsformed by beams of the plurality exiting from the injection opticalsystem are spatially separated from each other. The system furtherincludes a light-guiding optical element having an in-coupling gratingconfigured to admit a first beam of the plurality into the light-guidingoptical element while excluding a second beam of the plurality from thelight-guiding optical element, such that the first beam propagates bysubstantially total internal reflection through the light-guidingoptical element.

In one or more embodiments, each beam of the plurality differs fromother beams of the plurality in at least one light property. The atleast one light property may include color and/or polarization.

In one or more embodiments, the light source includes a plurality ofsub-light sources. The plurality of sub-light sources may be spatiallyseparated from each other. The plurality of sub-light sources mayinclude first and second groups of sub-light sources, and wheresub-light sources of the first group are displaced from sub-lightsources of the second group along an optical path of the imaging system.

In one or more embodiments, the light source is a unitary light sourceconfigured to produce the plurality of spatially separated light beams.The system may also include a mask overlay configured to segment lightfrom the light source into separate emission areas and positions.

In one or more embodiments, the system also includes a first spatiallight modulator configured to encode a first beam of the plurality withimage data. The system may also include a second spatial light modulatorconfigured to encode a second beam of the plurality with image data. Thefirst and second spatial light modulators may be configured to bealternatively activated. The first and second spatial light modulatorsmay have respective image fields that are spatially displaced from eachother. The first and second spatial light modulators may be configuredto generate images at different depth planes.

In one or more embodiments, the system also includes a plurality oflight-guiding optical elements having a respective plurality ofin-coupling gratings, the light source includes a plurality of sub-lightsources, and the respective pluralities of sub-light sources andin-coupling gratings are rotated around an optical axis relative to thefirst spatial light modulator.

In one or more embodiments, the system also includes a mask configuredto modify a shape of a pupil formed by a beam of the plurality adjacentto the light-guiding optical element. The system may also include anoptical element configured to modify a size of a pupil formed by a beamof the plurality adjacent to the light-guiding optical element. Theinjection optical system may have an eccentric cross-section along anoptical path of the imaging system. The in-coupling grating may beconfigured such that the first beam of the plurality encounters thein-coupling grating only once.

In one or more embodiments, the system also includes a pupil expanderconfigured to increase a numerical aperture of the light source. Thepupil expander may include a film having a prism pattern disposedthereon. The light source and the injection optical system may beconfigured such that the respective pupils formed by the plurality ofbeams exiting from the injection optical system have a plurality ofsizes.

In another embodiment directed to a method of displaying an image usingan optical system, the method includes a light source producing a firstlight beam. The method also includes a spatial light modulator encodingthe first beam with first image data. The method further includes aninjection optical system modifying the first beam such that the firstbeam addresses a first in-coupling grating on a first light-guidingoptical element, thereby entering the first light-guiding opticalelement, but does not enter a second light-guiding optical element.Moreover, the method includes the light source producing a second lightbeam. In addition, the method includes the spatial light modulatorencoding the second beam with second image data. The method alsoincludes the injection optical system focusing the second beam such thatthe second beam addresses a second in-coupling grating on the secondlight-guiding optical element, thereby entering the second light-guidingoptical element, but not entering the first light-guiding opticalelement.

In one or more embodiments, first and second pupils formed by the firstand second beams exiting from the injection optical system are spatiallyseparated from each other. The first and second pupils formed by thefirst and second beams exiting from the injection optical system mayalso have different sizes.

In one or more embodiments, the method also includes the light sourceproducing a third light beam. The method further includes the spatiallight modulator encoding the third beam with third image data. Moreover,the method includes the injection optical system focusing the third beamsuch that the third beam addresses a third in-coupling grating on athird light-guiding optical element, thereby entering the thirdlight-guiding optical element, but not entering the first or secondlight-guiding optical elements. The third beam exiting from theinjection optical system may form a third pupil. The first, second andthird pupils may be spatially separated from each other. The first,second and third pupils may form vertices of a triangle in a planeorthogonal to an optical path of the injection optical system. The firstbeam may include blue light and the first pupil is smaller than thesecond and third pupils. The first beam may include green light and thefirst pupil is larger than the second and third pupils.

In one or more embodiments, the method includes modifying the first andsecond beams to narrow respective shapes of the first and second pupils.

In one or more embodiments, the light source includes first and secondspatially separated sub-light sources configured to produce the firstand second beams. The method may include changing image color and/orimage depth by deactivating the second sub-light source whilemaintaining first sub-light source in an activated state.

In one or more embodiments, the first beam includes both red and bluelight, and the second beam includes green light.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of various embodiments ofthe present invention. It should be noted that the figures are not drawnto scale and that elements of similar structures or functions arerepresented by like reference numerals throughout the figures. In orderto better appreciate how to obtain the above-recited and otheradvantages and objects of various embodiments of the invention, a moredetailed description of the present inventions briefly described abovewill be rendered by reference to specific embodiments thereof, which areillustrated in the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered limiting of its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIGS. 1 to 3 are detailed schematic views of various augmented realitysystems;

FIG. 4 is a diagram depicting the focal planes of an augmented realitysystem according to still another embodiment;

FIG. 5 is a block diagram depicting an augmented reality systemaccording to one embodiment;

FIGS. 6 and 14 are detailed schematic views of various components ofaugmented reality systems according to two embodiments;

FIGS. 7A-7C, 8A-8C and 15A depict sub-pupil and super-pupilconfigurations generated by augmented reality systems according tovarious embodiments;

FIGS. 9 to 13 are schematic views of various components of augmentedreality systems according to various embodiments;

FIG. 15B depicts sub-pupils formed at the light-guiding optical elementsof an augmented reality system according to one embodiment;

FIG. 16 is an exploded view of various components of an augmentedreality system according to yet another embodiment;

FIGS. 17A and 17B depict a narrow injection optical system of anaugmented reality system according to one embodiment and the resultingsub-pupils and super-pupil formed thereby;

FIGS. 18A-18C and 19 depict sub-pupil and super-pupil shapes andconfigurations generated by augmented reality systems according tovarious embodiments;

FIGS. 20A and 20B depict sub-pupil and super-pupil shapes andconfigurations generated by augmented reality systems according tovarious 15 embodiments;

FIGS. 20C and 20D depict light-guiding optical elements of augmentedreality systems according to two embodiments, where the light-guidingoptical elements are configured for use with beams corresponding to thesub-pupils and super-pupils depicted in FIGS. 20A and 20B, respectively;

FIG. 21 depicts light-guiding optical elements of an augmented realitysystem according to one embodiment, where the light-guiding opticalelements are configured for use with specific wavelengths of light;

FIGS. 22A and 22B are exploded views of components of augmented realitysystems according to two embodiments;

FIGS. 22C and 22D depict sub-pupil and super-pupil configurationsgenerated by the augmented reality systems depicted in FIGS. 22A and22B, respectively;

FIGS. 23 and 24 are schematic views of components of augmented realitysystems according to two embodiments, wherein the systems have two SLMs;

FIG. 25 is a schematic view of various components of an augmentedreality system according to another embodiment;

FIGS. 26 to 28 and 30 are diagrams depicting components of augmentedreality systems according to various embodiments;

FIG. 29 is a detailed schematic view of separated sub-pupils formed bythe augmented reality system depicted in FIG. 28 ;

FIGS. 31 and 32 are exploded views of simple augmented reality systemsaccording to two embodiments;

FIG. 33 is a schematic view of a light source and a pupil expander of anaugmented reality system according to still another embodiment;

FIGS. 34A and 35A depict sub-pupil and super-pupil configurationsgenerated by augmented reality systems according to two embodiments;

FIGS. 34B and 35B depict display pixels generated by augmented realitysystems according to two embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the invention are directed to systems, methods,and articles of manufacture for implementing optical systems in a singleembodiment or in multiple embodiments. Other objects, features, andadvantages of the invention are described in the detailed description,figures, and claims.

Various embodiments will now be described in detail with reference tothe drawings, which are provided as illustrative examples of theinvention so as to enable those skilled in the art to practice theinvention. Notably, the figures and the examples below are not meant tolimit the scope of the present invention. Where certain elements of thepresent invention may be partially or fully implemented using knowncomponents (or methods or processes), only those portions of such knowncomponents (or methods or processes) that are necessary for anunderstanding of the present invention will be described, and thedetailed descriptions of other portions of such known components (ormethods or processes) will be omitted so as not to obscure theinvention. Further, various embodiments encompass present and futureknown equivalents to the components referred to herein by way ofillustration.

The optical systems may be implemented independently of AR systems, butmany embodiments below are described in relation to AR systems forillustrative purposes only.

Summary of Problem and Solution

One type of optical system for generating virtual images at variousdepths includes numerous optical components (e.g., light sources,prisms, gratings, filters, scan-optics, beam-splitters, mirrors,half-mirrors, shutters, eye pieces, etc.) that increase in number,thereby increasing the complexity, size and cost of AR and VR systems,as the quality of the 3-D experience/scenario (e.g., the number ofimaging planes) and the quality of images (e.g., the number of imagecolors) increases. The increasing size of optical systems withincreasing 3-D scenario/image quality imposes a limit on the minimumsize of AR and VR systems resulting in cumbersome systems with reducedefficiency.

The following disclosure describes various embodiments of systems andmethods for creating 3-D perception using multiple-plane focus opticalelements that address the problem, by providing optical systems withfewer components and increased efficiency. In particular, the systemsdescribed herein utilize light sources with spatially separatedsub-light sources and injection optical systems to generate spatiallyseparated light beams corresponding to respective sub-light sources.After these spatially separated light beams exit the injection opticalsystems, they focus down to spatially separated sub-pupils(corresponding to respective sub-light sources) adjacent light guidingoptical elements (“LOEs”; e.g., a planar waveguide). The sub-pupils canbe spatially separated from each other in the X, Y and Z directions. Thespatial separation of the sub-pupils allows spatial separation ofin-coupling gratings for distinct LOEs, such that each sub-pupiladdresses the in-coupling grating of a distinct LOE. Accordingly, LOEscan be selectively illuminated by activating and deactivating sub-lightsources. This optical system design takes advantage of separatedsub-pupils to reduce the number of optical elements between the lightsource and the LOEs, thereby simplifying and reducing the size of AR andVR systems.

Illustrative Optical Systems

Before describing the details of embodiments of the separated pupilinvention, this disclosure will now provide a brief description ofillustrative optical systems. While the embodiments can be used with anyoptical system, specific systems (e.g., AR systems) are described toillustrate the technologies underlying the embodiments.

One possible approach to implementing an AR system uses a plurality ofvolume phase holograms, surface-relief holograms, or light-guidingoptical elements that are embedded with depth plane information togenerate images that appear to originate from respective depth planes.In other words, a diffraction pattern, or diffractive optical element(“DOE”) may be embedded within or imprinted upon an LOE such that ascollimated light (light beams with substantially planar wavefronts) issubstantially totally internally reflected along the LOE, it intersectsthe diffraction pattern at multiple locations and at least partiallyexits toward the user's eye. The DOEs are configured so that lightexiting therethrough from an LOE are verged so that they appear tooriginate from a particular depth plane. The collimated light may begenerated using an optical condensing lens (a “condenser”).

For example, a first LOE may be configured to deliver collimated lightto the eye that appears to originate from the optical infinity depthplane (0 diopters). Another LOE may be configured to deliver collimatedlight that appears to originate from a distance of 2 meters (1/2diopter). Yet another LOE may be configured to deliver collimated lightthat appears to originate from a distance of 1 meter (1 diopter). Byusing a stacked LOE assembly, it can be appreciated that multiple depthplanes may be created, with each LOE configured to display images thatappear to originate from a particular depth plane. It should beappreciated that the stack may include any number of LOEs. However, atleast N stacked LOEs are required to generate N depth planes. Further,N, 2N or 3N stacked LOEs may be used to generate RGB colored images at Ndepth planes.

In order to present 3-D virtual content to the user, the AR systemprojects images of the virtual content into the user's eye so that theyappear to originate from various depth planes in the Z direction (i.e.,orthogonally away from the user's eye). In other words, the virtualcontent may not only change in the X and Y directions (i.e., in a 2Dplane orthogonal to a central visual axis of the user's eye), but it mayalso appear to change in the Z direction such that the user may perceivean object to be very close or at an infinite distance or any distance inbetween. In other embodiments, the user may perceive multiple objectssimultaneously at different depth planes. For example, the user may seea virtual dragon appear from infinity and run towards the user.Alternatively, the user may simultaneously see a virtual bird at adistance of 3 meters away from the user and a virtual coffee cup atarm's length (about 1 meter) from the user.

Multiple-plane focus systems create a perception of variable depth byprojecting images on some or all of a plurality of depth planes locatedat respective fixed distances in the Z direction from the user's eye.Referring now to FIG. 4 , it should be appreciated that multiple-planefocus systems typically display frames at fixed depth planes 202 (e.g.,the six depth planes 202 shown in FIG. 4 ). Although AR systems caninclude any number of depth planes 202, one exemplary multiple-planefocus system has six fixed depth planes 202 in the Z direction. Ingenerating virtual content at one or more of the six depth planes 202,3-D perception is created such that the user perceives one or morevirtual objects at varying distances from the user's eye. Given that thehuman eye is more sensitive to objects that are closer in distance thanobjects that appear to be far away, more depth planes 202 are generatedcloser to the eye, as shown in FIG. 4 . In other embodiments, the depthplanes 202 may be placed at equal distances away from each other.

Depth plane positions 202 are typically measured in diopters, which is aunit of optical power equal to the inverse of the focal length measuredin meters. For example, in one embodiment, depth plane 1 may be 1/3diopters away, depth plane 2 may be 0.3 diopters away, depth plane 3 maybe 0.2 diopters away, depth plane 4 may be 0.15 diopters away, depthplane 5 may be 0.1 diopters away, and depth plane 6 may representinfinity (i.e., 0 diopters away). It should be appreciated that otherembodiments may generate depth planes 202 at other distances/diopters.Thus, in generating virtual content at strategically placed depth planes202, the user is able to perceive virtual objects in three dimensions.For example, the user may perceive a first virtual object as being closeto him when displayed in depth plane 1, while another virtual objectappears at infinity at depth plane 6. Alternatively, the virtual objectmay first be displayed at depth plane 6, then depth plane 5, and so onuntil the virtual object appears very close to the user. It should beappreciated that the above examples are significantly simplified forillustrative purposes. In another embodiment, all six depth planes maybe concentrated on a particular focal distance away from the user. Forexample, if the virtual content to be displayed is a coffee cup half ameter away from the user, all six depth planes could be generated atvarious cross-sections of the coffee cup, giving the user a highlygranulated 3-D view of the coffee cup.

In one embodiment, the AR system may work as a multiple-plane focussystem. In other words, all six LOEs may be illuminated simultaneously,such that images appearing to originate from six fixed depth planes aregenerated in rapid succession with the light sources rapidly conveyingimage information to LOE 1, then LOE 2, then LOE 3 and so on. Forexample, a portion of the desired image, comprising an image of the skyat optical infinity may be injected at time 1 and the LOE 1090 retainingcollimation of light (e.g., depth plane 6 from FIG. 4 ) may be utilized.Then an image of a closer tree branch may be injected at time 2 and anLOE 1090 configured to create an image appearing to originate from adepth plane 10 meters away (e.g., depth plane 5 from FIG. 4 ) may beutilized; then an image of a pen may be injected at time 3 and an LOE1090 configured to create an image appearing to originate from a depthplane 1 meter away may be utilized. This type of paradigm can berepeated in rapid time sequential (e.g., at 360 Hz) fashion such thatthe user's eye and brain (e.g., visual cortex) perceives the input to beall part of the same image.

AR systems are required to project images (i.e., by diverging orconverging light beams) that appear to originate from various locationsalong the Z axis (i.e., depth planes) to generate images for a 3-Dexperience. As used in this application, light beams include, but arenot limited to, directional projections of light energy (includingvisible and invisible light energy) radiating from a light source.Generating images that appear to originate from various depth planesconforms or synchronizes the vergence and accommodation of the user'seye for that image, and minimizes or eliminates vergence-accommodationconflict.

FIG. 1 depicts a basic optical system 100 for projecting images at asingle depth plane. The system 100 includes a light source 120 and anLOE 190 having a diffractive optical element (not shown) and anin-coupling grating 192 (“ICG”) associated therewith. The diffractiveoptical elements may be of any type, including volumetric or surfacerelief. In one embodiment, the ICG 192 can be a reflection-modealuminized portion of the LOE 190. In another embodiment, the ICG 192can be a transmissive diffractive portion of the LOE 190. When thesystem 100 is in use, a “virtual” light beam from the light source 120enters the LOE 190 via the ICG 192 and propagates along the LOE 190 bysubstantially total internal reflection (“TIR”) for display to an eye ofa user. The light beam is “virtual” because it encodes an image of anon-existent “virtual” object or a portion thereof as directed by thesystem 100. It is understood that although only one beam is illustratedin FIG. 1 , a multitude of beams, which encode an image, may enter theLOE 190 from a wide range of angles through the same ICG 192. A lightbeam “entering” or being “admitted” into an LOE includes, but is notlimited to, the light beam interacting with the LOE so as to propagatealong the LOE by substantially TIR. The system 100 depicted in FIG. 1can include various light sources 120 (e.g., LEDs, OLEDs, lasers, andmasked broad-area/broad-band emitters). In other embodiments, light fromthe light source 120 may also be delivered to the LOE 190 via fiberoptic cables (not shown).

FIG. 2 depicts another optical system 100′, which includes a lightsource 120, and respective pluralities (e.g., three) of LOEs 190, andin-coupling gratings 192. The optical system 100′ also includes threebeam-splitters or dichroic mirrors 162 (to direct light to therespective LOEs) and three shutters 164 (to control when the LOEs areilluminated by the light source 120). The shutters 164 can be anysuitable optical shutter, including, but not limited to, liquid crystalshutters.

When the system 100′ is in use, the virtual light beam from the lightsource 120 is split into three virtual light sub-beams/beam lets by thethree-beam-splitters 162. The three beam-splitters 162 also redirect thesub-beams toward respective in-coupling gratings 192. After thesub-beams enter the LOEs 190 through the respective in-coupling gratings192, they propagate along the LOEs 190 by substantially TIR where theyinteract with additional optical structures resulting in display (e.g.,of a virtual object encoded by sub-beam) to an eye of a user. Thesurface of in-coupling gratings 192 on the far side of the optical pathcan be coated with an opaque material (e.g., aluminum) to prevent lightfrom passing through the in-coupling gratings 192 to the next LOE 190.In one embodiment the beam-splitters 162 can be combined with wavelengthfilters to generate red, green and blue sub-beams. In such anembodiment, three LOEs 190 are required to display a color image at asingle depth plane. In another embodiment, LOEs 190 may each present aportion of a larger, single depth-plane image area angularly displacedlaterally within the user's field of view, either of like colors, ordifferent colors (forming a “tiled field of view”). While all threevirtual light beamlets are depicted as passing through respectiveshutters 164, typically only one beamlet is selectively allowed to passthrough a corresponding shutter 164 at any one time. In this way, thesystem 100′ can coordinate image information encoded by the beam andbeamlets with the LOE 190 through which the beamlet and the imageinformation encoded therein will be delivered to the user's eye.

FIG. 3 depicts still another optical system 100″, having respectivepluralities (e.g., six) of beam-splitters 162, shutters 164, ICGs 192,and LOEs 190. As explained above during the discussion of FIG. 2 , threesingle-color LOEs 190 are required to display a color image at a singledepth plane. Therefore, the six LOEs 190 of this system 100″ are able todisplay color images at two depth planes.

The beam splitters 162 in optical system 100″ have different sizes. Theshutters 164 in optical system 100″ have different sizes correspondingto the size of the respective beam splitters 162. The ICGs 192 inoptical system 100″ have different sizes corresponding to the size ofthe respective beam splitters 162 and the length of the beam pathbetween the beam splitters 162 and their respective ICGs 192. In somecases, the longer the distance beam path between the beam splitters 162and their respective ICGs 192, the more the beams diverge and require alarger ICGs 192 to in-couple the light.

As shown in FIGS. 1-3 , as the number of depth planes, field tiles,and/or colors generated increases (e.g., with increased AR scenarioquality), the numbers of LOEs 190 and other optical system componentsincreases. For example, a single RGB color depth plane requires at leastthree single-color LOEs 190. As a result, the complexity and size of theoptical system also increases. The requirement for clean streams (i.e.,no light beam cross contamination or “cross-talk”) causes the complexityand size of the optical system to increase in a greater than linearfashion with increasing numbers of LOEs. In addition to thebeam-splitters 162 and LC shutters 164, more complicated optical systemscan include other light sources, prisms, gratings, filters, scan-optics,mirrors, half-mirrors, eye pieces, etc. As the number of opticalelements increases, so does the required working distance of the optics.The light intensity and other optical characteristics degrade as theworking distance increases. Further, the geometric constraint of thefield of view by the working distance imposes a practical limit on thenumber of optical elements in an optical system 100.

Separated Pupil Augmented Reality Systems

Referring now to FIG. 5 , an exemplary embodiment of a separated pupilAR system 1000 that addresses the issues of optical system complexityand size will now be described. The system 1000 uses stackedlight-guiding optical element assemblies 1090 as described above. The ARsystem 1000 generally includes an image generating processor 1010, alight source 1020, a controller 1030, a spatial light modulator (“SLM”)1040, an injection optical system 1060, and at least one set of stackedLOEs 1090 that functions as a multiple plane focus system. The systemmay also include an eye-tracking subsystem 1050. It should beappreciated that other embodiments may have multiple sets of stackedLOEs 1090, but the following disclosure will focus on the exemplaryembodiment of FIG. 5 .

The image generating processor 1010 is configured to generate virtualcontent to be displayed to the user. The image generating processor mayconvert an image or video associated with the virtual content to aformat that can be projected to the user in 3-D. For example, ingenerating 3-D content, the virtual content may need to be formattedsuch that portions of a particular image are displayed at a particulardepth plane while others are displayed at other depth planes. In oneembodiment, all of the image may be generated at a particular depthplane. In another embodiment, the image generating processor may beprogrammed to provide slightly different images to the right and lefteyes such that when viewed together, the virtual content appearscoherent and comfortable to the user's eyes.

The image generating processor 1010 may further include a memory 1012, aGPU 1014, a CPU 1016, and other circuitry for image generation andprocessing. The image generating processor 1010 may be programmed withthe desired virtual content to be presented to the user of the AR system1000. It should be appreciated that in some embodiments, the imagegenerating processor 1010 may be housed in the wearable AR system 1000.In other embodiments, the image generating processor 1010 and othercircuitry may be housed in a belt pack that is coupled to the wearableoptics. The image generating processor 1010 is operatively coupled tothe light source 1020 which projects the light associated with thedesired virtual content and one or more spatial light modulators(described below).

The light source 1020 is compact and has high resolution. The lightsource 1020 includes a plurality of spatially separated sub-lightsources 1022 that are operatively coupled to a controller 1030(described below). For instance, the light source 1020 may include colorspecific LEDs and lasers disposed in various geometric configurations.Alternatively, the light source 1020 may include LEDs or lasers of likecolor, each one linked to a specific region of the field of view of thedisplay. In another embodiment, the light source 1020 may comprise abroad-area emitter such as an incandescent or fluorescent lamp with amask overlay for segmentation of emission areas and positions. Althoughthe sub-light sources 1022 are directly connected to the AR system 1000in FIG. 5 , the sub-light sources 1022 may be connected to system 1000via optical fibers (not shown), as long as the distal ends of theoptical fibers (away from the sub-light sources 1022) are spatiallyseparated from each other. The system 1000 may also include condenser(not shown) configured to collimate the light from the light source1020.

The SLM 1040 may be reflective (e.g., a DLP DMD, a MEMS mirror system,an LCOS, or an FLCOS), transmissive (e.g., an LCD) or emissive (e.g. anFSD or an OLED) in various exemplary embodiments. The type of spatiallight modulator (e.g., speed, size, etc.) can be selected to improve thecreation of the 3-D perception. While DLP DMDs operating at higherrefresh rates may be easily incorporated into stationary AR systems1000, wearable AR systems 1000 typically use DLPs of smaller size andpower. The power of the DLP changes how 3-D depth planes/focal planesare created. The image generating processor 1010 is operatively coupledto the SLM 1040, which encodes the light from the light source 1020 withthe desired virtual content. Light from the light source 1020 may beencoded with the image information when it reflects off of, emits from,or passes through the SLM 1040.

Referring back to FIG. 5 , the AR system 1000 also includes an injectionoptical system 1060 configured to direct the light from the light source1020 (i.e., the plurality of spatially separated sub-light sources 1022)and the SLM 1040 to the LOE assembly 1090. The injection optical system1060 may include one or more lenses that are configured to direct thelight into the LOE assembly 1090. The injection optical system 1060 isconfigured to form spatially separated and distinct pupils (atrespective focal points of the beams exiting from the injection opticalsystem 1060) adjacent the LOEs 1090 corresponding to spatially separatedand distinct beams from the sub-light sources 1022 of the light source1020. The injection optical system 1060 is configured such that thepupils are spatially displaced from each other. In some embodiments, theinjection optical system 1060 is configured to spatially displace thebeams in the X and Y directions only. In such embodiments, the pupilsare formed in one X, Y plane. In other embodiments, the injectionoptical system 1060 is configured to spatially displace the beams in theX, Y and Z directions.

Spatial separation of light beams forms distinct beams and pupils, whichallows placement of in-coupling gratings in distinct beam paths, so thateach in-coupling grating is mostly addressed (e.g., intersected orimpinged) by only one distinct beam (or group of beams). This, in turn,facilitates entry of the spatially separated light beams into respectiveLOEs 1090 of the LOE assembly 1090, while minimizing entry of otherlight beams from other sub-light sources 1022 of the plurality (i.e.,cross-talk). A light beam from a particular sub-light source 1022 entersa respective LOE 1090 through an in-coupling grating (not shown in FIG.5 , see FIGS. 1-3 ) thereon. The in-coupling gratings of respective LOEs1090 are configured to interact with the spatially separated light beamsfrom the plurality of sub-light sources 1022 such that each spatiallyseparated light beam only intersects with the in-coupling grating of oneLOE 1090. Therefore, each spatially separated light beam mainly entersone LOE 1090. Accordingly, image data encoded on light beams from eachof the sub-light sources 1022 by the SLM 1040 can be effectivelypropagated along a single LOE 1090 for delivery to an eye of a user.

Each LOE 1090 is then configured to project an image or sub-image thatappears to originate from a desired depth plane or FOV angular positiononto a user's retina. The respective pluralities of LOEs 1090 andsub-light sources 1022 can therefore selectively project images(synchronously encoded by the SLM 1040 under the control of controller1030) that appear to originate from various depth planes or positions inspace. By sequentially projecting images using each of the respectivepluralities of LOEs 1090 and sub-light sources 1022 at a sufficientlyhigh frame rate (e.g., 360 Hz for six depth planes at an effectivefull-volume frame rate of 60 Hz), the system 1000 can generate a 3-Dimage of virtual objects at various depth planes that appear to existsimultaneously in the 3-D image.

The controller 1030 is in communication with and operatively coupled tothe image generating processor 1010, the light source 1020 (sub-lightsources 1022) and the SLM 1040 to coordinate the synchronous display ofimages by instructing the SLM 1040 to encode the light beams from thesub-light sources 1022 with appropriate image information from the imagegenerating processor 1010.

The AR system also includes an optional eye-tracking subsystem 1050 thatis configured to track the user's eyes and determine the user's focus.In one embodiment, only a subset of sub-light sources 1022 may beactivated, based on input from the eye-tracking subsystem, to illuminatea subset of LOEs 1090, as will be discussed below. Based on input fromthe eye-tracking subsystem 1050, one or more sub-light sources 1022corresponding to a particular LOE 1090 may be activated such that theimage is generated at a desired depth plane that coincides with theuser's focus/accommodation. For example, if the user's eyes are parallelto each other, the AR system 1000 may activate the sub-light sources1022 corresponding to the LOE 1090 that is configured to delivercollimated light to the user's eyes (e.g., LOE 6 from FIG. 4 ), suchthat the image appears to originate from optical infinity. In anotherexample, if the eye-tracking sub-system 1050 determines that the user'sfocus is at 1 meter away, the sub-light sources 1022 corresponding tothe LOE 1090 that is configured to focus approximately within that rangemay be activated instead. It should be appreciated that, in thisparticular embodiment, only one group of sub-light sources 1022 isactivated at any given time, while the other sub-light sources 1020 aredeactivated to conserve power.

The AR system 2000 depicted in FIG. 6 is configured to generatesub-pupils 302 that are spatially separated in the X, Y and Zdirections. The light source 2020 in this system 2000 includes twogroups of sub-light sources 2022 a, 2022 b that are displaced from eachother in the X, Y and Z (i.e., along the optical path) directions. Thesystem 2000 also includes a condenser 2070, an optional polarizer 2072,a beam-splitter 2026, an SLM 2024, an injection optical system 2060 anda stack of LOEs 2090. In use, the plurality of light beams from thesub-light sources 2022 a, 2022 b pass through the above-listed systemcomponents in the order listed. The displacement of sub-light sources2022 a, 2022 b in the X, Y and Z directions generates beams with focalpoints that are displaced in the X, Y and Z directions, therebyincreasing the number of spatially separated sub-pupils 302 and LOEs2090 that can be illuminated in the system 2000.

FIGS. 7A to 7C and 8A to 8C depict various spatial arrangements ofsub-pupils 302 within a super-pupil 300 generated by various AR systems2000 similar to the one depicted in FIG. 6 . While the sub-pupils 302are depicted as spatially separated in the X, Y plane, the sub-pupils302 can also be spatially separated in the Z direction. Sub-pupils 302formed by beams having the same color may be maximally spatiallyseparated (as shown in FIGS. 8A to 8C) to reduce cross-talk between LOEs2090 configured to propagate light of the same color. Further, insystems 2000 like the one depicted in FIG. 6 , which form sub-pupils 302separated from each other in Z direction, color and/or depth planeand/or field of view solid-angle segment can be switched by switchingsub-light sources 2022 a, 2022 b without the need for shutters.

FIGS. 9 to 11 depict AR systems 2000 in which the light source 2020(e.g., an angularly displaced RGB flat panel having spatially displacedred, green and blue sub-light sources (e.g., LEDs)) is angularlydisplaced (relative to the optical path) to produce spatially displacedcolor sub-pupils adjacent to respective LOEs 2090. Angularly displacingthe light source 2020 changes the relative locations of the red, greenand blue sub-light sources in the Z direction in addition to the X and Ydirections. In FIG. 9 , the spatially displaced light beams from thelight source 2020 are encoded with image data using a digital lightprocessing (“DLP”) SLM 2024. The light beams reflecting off of the DLPSLM 2024 enter the injection optical 2060, which further spatiallyseparates the light beams, thereby forming spatially separatedsub-pupils corresponding to each beam. The spatially separated andcollimated light beams enter respective LOEs 2090 through respectivein-coupling gratings (not shown), and propagate in the LOEs 2090 asdescribed above. In one embodiment, the three light beams depicted inFIG. 9 can be light of different wavelengths (e.g., red, green andblue). By modifying the configuration of various components of the ARsystem 2000, the spatial separation of the sub-pupils can be differentfrom the spatial separation of the sub-light sources.

The system 2000 depicted in FIG. 10 is similar to the one depicted inFIG. 9 , except that the beams from the light source 2020 are focused onthe surface of the SLM 2024, which is a MEMS mirror SLM 2024. Theinjection optical system 2060 in FIG. 10 is configured to furtherspatially separate light reflecting from the mems mirror SLM 2024 togenerate spatially separated sub-pupils corresponding to each beam.

The system 2000 depicted in FIG. 11 is similar to the one depicted inFIG. 9 , except that the light source 2020 is a fiber scanned display(“FSD”), which is a combined RGB image source. The SLM 2024 is avolume-phase or blazed holographic optical element that both re-directsand spatially separates the RGB beam from the FSD 2020 into spatiallyseparated sub-beams including different color light and/or lightconfigured for different depth planes. In one embodiment, threesub-beams include red, green and blue light, respectively. The injectionoptical system 2060 in FIG. 11 functions similarly to the system 2060 inFIG. 9 to generate spatially separated sub-pupils corresponding to eachsub-beam.

The system 2000 depicted in FIG. 12 is similar to the one depicted inFIG. 9 , except that a beam-splitter 2026 is added to the optical path.Spatially displaced light beams from the light source 2020 reflect offthe beam-splitter 2026 and onto the SLM 2024, which in this embodimentis an LCOS or an FLCOS. The spatially displaced light-beams reflect offthe SLM 2024, through the beam-splitter 2026, and into the injectionoptical system 2060. The injection optical system 2060 in FIG. 12functions similarly to the system 2060 in FIG. 9 to generate spatiallyseparated sub-pupils corresponding to each beam.

FIG. 13 depicts an AR system 2000 very similar to the one depicted inFIG. 12 . In the system 2000 depicted in FIG. 10 , the beam-splitter2026 from the system 2000 depicted in FIG. 12 is replaced with thepolarizing beam-splitter 2028, which may include a reflective wire-gridpolarizer or a polarization-sensitive dichroic-coated layer. The ARsystem 2000 also includes a condenser 2070 disposed between the lightsource 2020 and the wire grid polarizer 2028. Light beams from the lightsource 2020 pass through the condenser 2070 and the polarizingbeam-splitter 2028, and onto an LCOS SLM 2024. The light beams reflectoff the SLM 2024 and the beam-splitter 2026, and into the injectionoptical system 2060. The injection optical system 2060 in FIG. 13functions similarly to the system 2060 in FIG. 12 to generate spatiallyseparated sub-pupils corresponding to each beam. FIG. 13 shows that thesub-pupils can be spatially separated in the X, Y and Z directionsrelative to the optical path. FIG. 13 depicts three lenses forming theinjection optical system 2060, however other embodiments of injectionoptical systems 2060 can include fewer or more lenses. For instance,FIG. 14 depicts an AR system 2000 including an injection optical system2060 having a relay lens 2080 to convert a divergent set of beams into aconvergent set of beams and external pupils coincident on and forpropagation by distinct LOEs 2090.

FIG. 15A depicts a spatial arrangement of sub-pupils 302 in the X, Yplane within a super-pupil 300 generated by an AR system 2000 accordingto one embodiment. FIG. 15B depicts a stack of six LOEs 2090 of thesystem 2000 and the respective areas 306 where the light beams formingthe sub-pupils 302 depicted in FIG. 15A intersect each of the LOEs 2090.The areas 306 have different sizes due to the varying Z distances of therespective LOEs 2090 from the pupils 302 shown in FIG. 15A and otheroptical properties. As shown in FIG. 15B, the beams forming the varioussub-pupils 302 can be selectively coupled into respective LOEs 2090 byforming in-coupling gratings adjacent the areas 306 on the respectiveLOEs 2090 that are addressed by the respective beams.

FIG. 16 depicts another embodiment of an AR system 2000 that isconfigured to generate a spatial arrangement of sub-pupils 302 in the X,Y plane within a super-pupil 300 similar to the pattern depicted in FIG.15A. The system 2000 includes a light source 2020 having a plurality ofsub-light sources that are spatially separated from each other. Thesystem 2000 also includes a condenser 2070, a polarizing beam-splitter2026, an LCOS SLM 2024, an injection optical system 2060 and a stack ofLOEs 2090. Each LOE 2090 of the stack has an in-coupling grating 2092that is co-located with an area 306 of intersection by a distinct beam,as described above. Consequently, each beam is propagated along a singleLOE 2090 to the user's eye.

The disclosed AR system 2000 utilizes spatially separated sub-lightsources 2022 and injection optical systems 2060 to enable distinct beamsand sub-pupils 302 to address in-coupling gratings configured to admitlight into distinct LOEs 2090. Accordingly, the systems 2000 enable aplurality of sub-light sources 2022 to address respective LOEs 2090while minimizing the number of optical components therebetween. Thisboth reduces system size and increases system efficiency.

Other Embodiments and Features

The geometry of optical components in the AR system 2000 can be selectedto maintain spatial separation of sub-pupils 302 while reducing the sizeof the system. For instance, in FIG. 17A, the cross-sectional shape ofinjection optical system 2060 is a rounded rectangle (i.e., a rectanglewith rounded corners and rounded short sides). As shown in FIGS. 17A and17B, if the beams addressing the SLM 2024 are spatially separated fromeach other, the injection optical system 2060 in this embodiment willform similar spatially separated sub-pupils 302.

FIGS. 18A to 18C depict various spatial arrangements and shapes ofsub-pupils 302 in the X, Y plane within respective super-pupils 300generated by various AR systems 2000. In addition to controlling thespatial arrangements of sub-pupils 302, the AR systems 2000 are alsoconfigured to control the shape of the sub-pupils. The varioussub-/super-pupil shapes include square/oval (FIG. 18A), pie/circle (FIG.18B) and concentric annuli/circle (FIG. 18C). In one embodiment, thepupil shapes are formed by masking/filtering at or near the sub-lightsources 2022. In another embodiment, the pupil shapes are formed usingdiffractive optics. In still another embodiment (e.g., FIG. 18C), thepupil shapes are formed by Z axis displacement of sub-light sources2022.

FIG. 19 depicts another spatial arrangement of sub-pupils 302 in the X,Y plane within a super-pupil 300 generated by an AR system 2000. Inaddition to spatial displacement, the sub-pupils 302, 302 s in FIG. 19also have two or more sizes. In one embodiment, the smaller sub-pupils302 s are formed by beams including blue light, and larger sub-pupils302 are formed by beams including red and green light. An AR system 2000forming the sub-pupil pattern shown in FIG. 19 can take advantage of thehuman eye's reduced ability to focus blue light (e.g., relative to redand green light) and increased ability to focus green light (e.g.relative to red and blue light) to present more pupils, and thereforemore visual information, in a super-pupil 300 of a given size (e.g., bydisplaying blue sub-pupils 302 s having a reduced size).

Modulating the size (e.g., diameter) of the sub-pupils 302, 302 s (e.g.,based on the size and/or optics associated with the light sources)facilitates more efficient optical system design. Larger sub-pupils(e.g., 302) can provide increased image resolution in optical systemscompared to sub-smaller pupils (e.g., 302 s). Accordingly, designing anoptical system having a plurality of sub-pupil sizes enables selectionof depth of focus based on color and/or depth plane being addressed.Optical systems 2000 can include smaller blue light sources and largerred and green light sources to achieve smaller blue sub-pupils 302 s.This design takes advantage of the human eye's inability to focus bluelight as well as red and green light. As a result, blue light resolutioncan be lower than the resolution for red and green light. This designallows for an improved mix of sub-pupils 302, 302 s within thesuper-pupil 300 of the optical system 2000, and may also allow for moresub-pupils 302, 302 s (and therefore more depth plane channels) to beincorporated without substantially increasing the size of the opticalsystem 2000.

FIGS. 20A and 20B depict two sets of sub-pupils 302 in the X, Y planewithin respective super-pupils 300 generated by respective AR systems2000. While the areas of corresponding sub-pupils 302 in FIGS. 20A and19B are approximately equal, the shapes of the sub-pupils 302 in FIGS.20A (circles) and 20B (rectangles) are different. An AR system 2000forming the sub-pupil pattern shown in FIG. 20B can take advantage ofthe human eye's focus being preferentially driven by one dimension(e.g., the long axis of the rectangular sub-pupil 300) over the other(e.g., the short axis of the rectangular sub-pupil 300) to enable moreefficient sub-pupil stacking relative to user focus.

The sub-pupil 302 shape in FIG. 20B can also reduce the size ofin-coupling gratings 2092 (compare FIG. 20D to FIG. 20C). This, in turn,reduces the number of encounters of the beam with the in-couplinggrating 2092, which reduces unintended out-coupling of light from theLOE 2090 (by second encounters with the in-coupling grating 2092),thereby increasing the intensity of the beam propagated along the LOE2090.

FIG. 21 depicts an AR system 2000 where two light beams are configuredto provide light that propagates along three LOEs 2090. The system 2000includes sub-light sources (not shown) and an SLM (not shown) thatgenerate first and second light beams 304 a, 304 b that are spatiallyseparated from each other. The first light beam 304 a includes both redand blue light, forming a magenta beam. The second light beam 304 bincludes green light. The first beam 304 a is aligned (e.g., by theinjection optical system (not shown)) with in-coupling gratings 2092formed on first and second LOEs 2090 a, 2090 b, which are tuned topropagate blue and red light, respectively. Due to the properties of thefirst LOE 2090 a, any red light entering the first LOE 2090 a will notbe propagated therein. A yellow filter 2094 is placed betweenin-coupling gratings 2092 formed on first and second LOEs 2090 a, 2090 bto absorb any blue light passing through the first LOE 2090 a.Accordingly, only red light from the first beam 304 a enters the secondLOE 2090 b and is propagated therein.

As with previously described AR systems, the second beam 304 b passesthrough the first and second LOEs 2090 a, 2090 b and enters the thirdLOE 2090 c (through in-coupling grating 2092), which is tuned topropagate green light. The AR system 2000 depicted in FIG. 21 takesadvantage of the ability to combine red and blue light in a single beamto reduce the number of beams (and sub-light sources) to provide lightfor LOEs of differing primary colors, thereby reducing the size of theAR system 2000.

FIGS. 22A and 22B depict two alternative AR systems 2000 havinginjection optical systems 2060 a, 2060 b with different geometries. As aresult, the AR systems 2000 generate different sub-pupil 302/super-pupil300 patterns (see FIGS. 22C and 22D). The AR systems 2000 depicted inFIGS. 22A and 22B also have beam-splitters 2026 a, 2026 b with differentgeometries and optical properties to conform to the shapes of therespective injection optical systems 2060 a, 2060 b. As can be seen fromthe sub-pupil 302/super-pupil 300 patterns in FIGS. 22C and 22D, the ARsystem 2000 depicted in FIG. 22B generates twice as many sub-pupils 302as the AR system 2000 depicted in FIG. 22A in less than twice thesuper-pupil 300 size. Similar size savings extends to the injectionoptical systems 2060 a, 2060 b and the beam-splitters 2026 a, 2026 b, asshown in FIGS. 22A and 22B.

In one embodiment, the six sub-pupils 302 in the pattern depicted inFIG. 22D include magenta light, similar to the system 2000 depicted inFIG. 21 . Using magenta light and LOE 2090 structures like thosedepicted in FIG. 21 , the AR system 2000 depicted in FIG. 22B canprovide light for three times as many LOEs 2090 as the AR system 2000depicted in FIG. 22A. For instance, the AR system 2000 depicted in FIG.22A generates six sub-pupils 302 to provide light for six LOEs 2090(e.g., two depth layers with three colors each). On the other hand, theAR system 2000 depicted in FIG. 22B generates 12 sub-pupils 302 toprovide light for 18 LOEs 2090 (e.g., six depth layers with three colorseach). This three-fold increase in the number of LOEs 2090 is achievedwith less than a two-fold increase in super-pupil 300 size, injectionoptical system 2060 size and beam-splitter 2026 size.

FIG. 23 depicts still another embodiment of an AR system 2000. Like theAR system 2000 depicted in FIG. 13 , this AR system 2000 includes alight source 2020 having two groups of sub-light sources 2022 a, 2022 b,a condenser 2070, an optional polarizer 2072, a beam-splitter 2026, afirst SLM 2024 a, an injection optical system 2060 and a stack of LOEs2090. In addition to those optical elements, the system 2000 alsoincludes an optional half-wave plate 2074 (between the condenser 2070and the optional polarizer 2072), a second SLM 2024 b (between the beamsplitter 2026 and the injection optical system 2060) and a depolarizer2076 (between the first and second SLMs 2024 a, 2024 b and the injectionoptical system 2060).

In use, the plurality of light beams from the sub-light sources 2022 a,2022 b pass through or reflect off of the above-listed system componentsin the order listed, as modified by the three added components. As withthe AR system 2000 depicted in FIG. 13 , the displacement of sub-lightsources 2022 a, 2022 b in the Z direction generates beams with focalpoints that are displaced in the Z direction, thereby increasing thenumber of spatially separated sub-pupils 302 and LOEs 2090 that can beilluminated in the system 2000. In some embodiments, the first andsecond SLMs 2024 a, 2024 b can have superimposed image fields and can bealternatively activated to reduce system latency and increase frame rate(e.g., using two 30 Hz SLMs 2024 a, 2024 b to project images at 60 Hz).In alternative embodiments, the first and second SLMs 2024 a, 2024 b canhave image fields that are displaced by half a pixel and be concurrentlyactivated to increase system resolution. In those embodiments, the firstand second SLMs 2024 a, 2024 b can be configured to increase the numberof depth planes by temporal multiplexing. In another embodiment, thefirst and second SLMs 2024 a, 2024 b can produce image fieldssimultaneously, such that two depth planes may be displayedsimultaneously within the viewer field of view.

FIG. 24 depicts an AR system 2000 very similar to the one depicted inFIG. 23 . In the system 2000 depicted in FIG. 24 , the beam-splitter2026 from the system 2000 depicted in FIG. 23 is replaced with the wiregrid polarizer 2028, eliminating the need for the optional polarizer2072 in FIG. 23 . The system 2000 in FIG. 24 functions in a very similarfashion to the system 2000 in FIG. 23 to accommodate two SLMs 2024 a,2024 b, which is described above. FIG. 24 depicts three lenses formingthe injection optical system 2060, however other embodiments ofinjection optical systems 2060 can include fewer or more lenses.

FIG. 25 depicts yet another embodiment of an AR system 2000. The system2000 includes two sets of light sources 2020, SLMs 2024,illumination-shaping optics (beam-splitters 2026, polarizers 2072,etc.), injection optics 2060 configured to cooperatively direct light(and image data) to a stack of LOEs 2090. The independent sets ofoptical elements generate independent sets of sub-pupils that arespatial separated from each other, thereby effectively doubling thenumber of LOEs 2090 that can be illuminated with the system 2000 whileminimizing system 2000 size. *

FIG. 26 schematically depicts a simple AR system 2000 configured togenerate spatially separated sub-pupils 302. The system 2000 includes alight source 2020, a condenser 2070, a transmissive SLM 2024, aninjection optical system 2060, and an LOE 2090. The light source 2020can include three sub-light sources 2022 a, 2022 b, 2022 c (e.g., LEDs)having 400 μm diameters and spaced 400 μm apart from each other (edge toedge). The condenser 2070 and the injection optical system 2060 can eachhave an effective focal length of 6.68 mm. The transmissive SLM 2024 canbe a LCOS having specifications of 1080×1080×4.2 um and 3.2074 mmsemi-d. Using such components, the system 2000 can generate threesub-pupils 302 a, 302 b, 302 c corresponding to the three sub-lightsources 2022 a, 2022 b, 2020 c and each having 400 μm diameters andspaced 400 μm apart from each other at the LOE 2090.

FIG. 27 depicts another embodiment of an AR system 2000 configured togenerate a sub-pupil 302. The system 2000 includes a sub-light source(not shown), a beam-splitter 2026, half-wave plate 2074, an injectionoptical system 2060, and a plurality of LOE 2090. The light source 2020can include a plurality of sub-light sources (e.g., LEDs). Thebeam-splitter 2026 can be a 10 mm polarizing beam splitter (PBS) prism.The injection optical system 2060 can include three lenses. Using suchcomponents, the system 2000 can generate a sub-pupil 302 disposed at theback of the second LOE 2090 in the six LOE 2090 stack and correspondingto the sub-light source.

FIG. 28 is another depiction of the AR system 2000 depicted in FIG. 27 .The optical elements in the two systems are the same, however, theoptical elements in the system 2000 depicted in FIG. 28 is shown withray sets that generate three sub-pupils 302 disposed at the back of thesecond LOE 2090 in the six LOE 2090 stack. FIG. 28 shows the ray setsfor the full super pupil. FIG. 29 shows the three sub-pupils 302 fromFIG. 28 in detail.

FIG. 30 depicts another embodiment of an AR system 2000 very similar tothe one depicted in FIG. 10 . The system 2000 includes a light source2020 including a plurality of sub-light sources 2022 (e.g., LEDs and/orfibers attached to sub-light sources), two lenses forming a condenser2070, a linear polarizer 2072, a triple band-pass filter 2078, abeam-splitter 2026, an SLM 2024 (e.g., LCOS), a half-wave plate 2074, aninjection optical system 2060, and two LOEs 2090. The system isconfigured to generate sub-pupils 302 at the back of the second LOE 2090that correspond to a 1:1 image of the sub-light sources 2022. In theembodiment depicted in FIG. 30 , the optical path forms an approximateright angle with a first length of about 29.9 mm between the lightsource 2020 and the beam-splitter 2026 and a second length of about 26mm between the beam-splitter 2026 and the second LOE 2090.

FIG. 31 is a schematic view of simple a simple AR system 2000 configuredto generate a sub-pupil 302 corresponding to a light source 2020. Thesystem 2000 includes an LED light source 2020, a condenser 2070, an SLM2024, a relay optical system 2080, an injection optical system 2060, andan LOE 2090. The condenser 2070 may have a focal length of 40 mm. TheSLM 2024 may be an LCOS. The relay optical system 2080 may include twolenses: a first lens with a focal length of 100 mm; and a second lenswith a focal length of 200 mm. The injection optical system may be acompound lens with an effective focal length of 34.3 mm. Using thissystem 2000, a 3.5 mm separation between LED light sources 2020generates an approximate 2.25 mm separation between sub-pupils 302 atthe LOE 2090.

FIG. 32 is a schematic view of another simple AR system 2000 verysimilar to the one depicted in FIG. 31 . The optical elements in the twosystems 2000 are very similar. The differences are: (1) the second lens(forming part of the relay optical system 2080) has a focal length of120 mm; and (2) the injection optical system has an effective focallength of 26 mm. Using this system 2000, a 3.5 mm separation between LEDlight sources 2020 generates an approximate 3.2 mm separation betweensub-pupils 302 at the LOE 2090.

In another embodiment, an AR system may be configured to providemultiplanar focusing simultaneously. For example, with threesimultaneous focal planes, a primary focus plane (based upon measuredeye accommodation, for example) could be illuminated by activatingcorresponding sub-light source, and a +margin and −margin (i.e., onefocal plane closer, one farther out) could also be illuminated byactivating respective sub-light sources to provide a large focal rangein which the user can accommodate before the planes need to be updated.This increased focal range can provide a temporal advantage if the userswitches to a closer or farther focus (i.e., as determined byaccommodation measurement). Then the new plane of focus could be made tobe the middle depth of focus plane, with the + and −margins again readyfor a fast switchover to either one while the system catches up.

In embodiments where each of the LOEs 2090 receives and propagatesinjected light from a separate corresponding sub-light source 2022, eachsub-light source 1022 can operate at a reasonable speed, while thesystem 2000 maintains a sufficiently high refresh rate to rapidlygenerate different images/portions of the images to be injected intomultiple LOEs 2090. For example, a first LOE 2090 may be first injectedwith light from a first sub-light source 1022 that carries the image ofthe sky encoded by the SLM 1040 at a first time. Next, a second LOE 2090may be injected with light from a second sub-light source 1022 thatcarries the image of a tree branch encoded by the SLM 1040 at a secondtime. Then, a third LOE 2090 may be injected with light from a thirdsub-light source 1022 that carries the image of a pen encoded by thatSLM 1040 at a third time. This process can be repeated to provide aseries images at various depth planes. Thus, by having multiplesub-light sources 2022 instead of a single light source 2020 rapidlygenerating all the images to be fed into multiple LOEs 2090, eachsub-light source 2022 can operate at a reasonable speed to inject imagesonly to its respective LOE 2090.

In another embodiment of an AR system 1000 including an eye-trackingsubsystem 1050, two sub-light sources 1022 corresponding to two LOEs1090 having depth planes that are situated close together may besimultaneously activated to build in an allowance of error in theeye-tracking subsystem and account for other system deficiencies byprojecting the virtual content not just on one depth, but at two depthplanes that are in close proximity to each other and the detected usereye focus/accommodation.

In still another embodiment of an AR system 1000, to increase the fieldof view of optics, a tiling approach may be employed including two (ormore) sets of stacked LOEs 1090, each having a corresponding pluralityof sub-light sources 1022. Thus, one set of stacked LOEs 1090 andcorresponding sub-light sources 1022 may be configured to delivervirtual content to the center of the user's eye, while another set ofstacked LOEs 1090 and corresponding sub-light sources 1022 may beconfigured to deliver virtual content to the periphery of the user'seyes. Similar to the embodiment depicted in FIG. 5 and described above,each stack may comprise six LOEs 1090 for six depth planes. Using bothstacks together, the user's field of view is significantly increased.Further, having two different stacks of LOEs 1090 and two pluralities ofcorresponding sub-light sources 1022 provides more flexibility such thatslightly different virtual content may be projected in the periphery ofthe user's eyes compared to virtual content projected to the center ofthe user's eyes. More details on the tiling approach are described inabove-referenced U.S. Prov. Patent Application Ser. No. 62/005,865, thecontents of which have been previously incorporated by reference.

Pupil Expanders

It should be appreciated that the stacked DOEs/light-guiding opticalelements 1090, 2090 discussed above can additionally function as an exitpupil expander (“EPE”) to increase the numerical aperture of a lightsource 1020, 2020, thereby increasing the resolution of the system 1000,2000. The light source 1020, 2020 produces light of a smalldiameter/spot size, and the EPE can expand the apparent pupil of lightexiting from the light-guiding optical element 1090, 2090 to increasethe system resolution. In other embodiments of the AR system, the systemmay further comprise an orthogonal pupil expander (“OPE”) in addition toan EPE to expand the light in both the X and Y directions. More detailsabout the EPEs and OPEs are described in the above-referenced U.S. Prov.Patent Application Ser. No. 61/909,174 and U.S. Prov. Patent ApplicationSer. No. 62/005,807, the contents of which are hereby expressly andfully incorporated by reference in their entirety, as though set forthin full.

Other types of pupil expanders may be configured to function similarlyin systems that employ light sources 1020, 2020. Although light sources1020, 2020 offer high resolution, brightness and are compact, they havea small numerical aperture (i.e., small spot size). Thus, AR systems1000, 2000 typically employ some type of pupil expander that essentiallyworks to increase the numerical aperture of the generated light beams.While some systems may use DOEs that function as EPEs and/or OPEs toexpand the narrow beam of light generated by light sources 1020, 2020,other embodiments may use diffusers to expand the narrow beam of light.The diffuser may be created by etching an optical element to createsmall facets that scatter light. In another variation, an engineereddiffuser, similar to a diffractive element, may be created to maintain aclean spot size with desirable numerical aperture, which is similar tousing a diffractive lens. In other variations, the system may include aPDLC diffuser configured to increase the numerical aperture of the lightgenerated by the light source 1020, 2020.

FIG. 33 depicts a sub-light source 2022 (e.g., an LED) and a pupilexpander 2024, both of which are configured for use in an AR system 2000to generate a sub-pupil 302 corresponding to the sub-light source 2022.The pupil expander 2024 is a film 2023 having a prism pattern disposedthereon. The prism pattern modifies the beam emanating from thesub-light source 2022 to change the apparent size of the sub-lightsource 2022 from the actual source size 2022 s to a larger virtualsource size 2024 s. The virtual source size 2024 s can also be modifiedby changing the distance between the sub-light source 2022 and the pupilexpander 2024.

Reducing SLM Artifacts

FIG. 34A shows a spatial arrangement of sub-pupils 302 within asuper-pupil 300 similar to the ones depicted in FIGS. 14B and 15A. Asshown in FIG. 34A, AR systems 2000 can be configured such that therespective sub-pupils 302 are spatially separated in the X, Y plane.FIG. 34A also depicts artifacts 308 formed by diffraction of the lightbeam corresponding to the sub-pupil 302 c at approximately one o'clockin the circular super-pupil 300. The light beam is diffracted by the SLM(e.g., DLP or LCOS) pixel boundaries and structures, and forms a seriesof artifacts 308 that are aligned with sub-pupil 302 c along the X and Yaxes.

The artifacts 308 are aligned along the X and Y axes because of thestructure of the SLM, which corresponds to the structure of the displaypixels (shown in FIG. 34B). Returning to FIG. 34A, it is apparent thattwo artifacts 308 a, 308 b at least partially overlap respectivesub-pupils 302 a, 302 b. Accordingly, in the system 2000 correspondingto the sub-pupil 302 pattern depicted in FIG. 34A, light for the beamcorresponding to sub-pupil 302 c will enter sub-pupils 302 a and 302 b.The artifacts 308 a, 308 b will generate undesirable artifacts (i.e.,stray light) in the images intended to be displayed through pupils 308 aand 308 b. While FIG. 34A depicts only artifacts 308 corresponding tosub-pupil 302 c, each of the other sub-pupils 302 will have their ownset of artifacts (not shown for clarity). Accordingly, cross-talk willincrease proportional to the number of sub-pupils 302 in the system2000.

FIG. 35A depicts a spatial arrangement of sub-pupils 302 within asuper-pupil 300 similar to the one shown in FIG. 34A. However, thesub-light sources 2022 and the in-coupling gratings of the AR system2000 have been rotated (e.g., approximately 30 degrees) clockwise aroundthe optical axis relative to the SLM in order to reduce the SLMgenerated diffractive cross-talk between beams. The artifacts 308 remainaligned along the X and Y axes because of the structure of the SLM,which corresponds to the structure of the display pixels (shown in FIG.35B). As shown in FIG. 35A, rotating the sub-light sources 2022 relativeto the SLM and display pixel grid reduces overlap between diffractedenergy and in-coupling gratings, thereby reducing stray light, contrastissues and color artifacts. In particular, artifacts 308 a and 308 b nolonger overlap sub-pupils 302 a and 302 b. However, artifact 308 d nowpartially overlaps sub-pupil 302 d, although to a lesser extent than theoverlaps depicted in FIG. 34A. Accordingly, in this embodiment, thesystem 2000 is configured such that the positions of the sub-lightsources 2022 and in-coupling gratings are rotated (e.g., about 30degrees) around the optical axis relative to the SLM in order to reducethe (SLM generated) diffractive cross-talk between beams.

The above-described AR systems are provided as examples of variousoptical systems that can benefit from more space efficient optics.Accordingly, use of the optical systems described herein is not limitedto the disclosed AR systems, but rather applicable to any opticalsystem.

Various exemplary embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intended to be within the scopeof claims associated with this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Exemplary aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the invention interms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention. Forexample, the above-described process flows are described with referenceto a particular ordering of process actions. However, the ordering ofmany of the described process actions may be changed without affectingthe scope or operation of the invention. The specification and drawingsare, accordingly, to be regarded in an illustrative rather thanrestrictive sense.

What is claimed is:
 1. A method of operating an AR system to display an image viewable by a user's eyes, the method comprising: tracking, by an eye-tracking subsystem, a position of the user's eyes; determining, based on the position, a focus depth of the user's eyes; selecting, from a plurality of light-guiding optical elements, a subset of light-guiding optical elements configured to focus light at a depth plane corresponding to the focus depth of the user's eyes; producing a plurality of light beams using a subset of sub-light sources of a plurality of sub-light sources, the subset of sub-light sources being configured to illuminate the subset of light-guiding optical elements; and imaging the plurality of light beams through an imaging system and onto the subset of light-guiding optical elements such that the image is generated at the depth plane corresponding to the focus depth of the user's eyes.
 2. The method of claim 1, wherein the subset of sub-light sources are further configured to produce the plurality of light beams such that others of the plurality of light-guiding optical elements are not illuminated.
 3. The method of claim 1, wherein each sub-light source of the plurality of sub-light sources is configured to produce a plurality of light beams and wherein each light beam of the plurality of light beams is spatially separated.
 4. The method of claim 1, wherein imaging the plurality of light beams through the imaging system comprises encoding the plurality of light beams with image data using a spatial light modulator to provide a plurality of encoded light beams.
 5. The method of claim 4, wherein imaging the plurality of light beams through the imaging system further comprises modifying the plurality of encoded light beams using an injection optical system.
 6. The method of claim 5, wherein the injection optical system is characterized by an eccentric cross-section along an optical path of the imaging system.
 7. The method of claim 4, wherein each light-guiding optical element of the plurality of light-guiding optical elements comprises a respective in-coupling grating configured to admit the plurality of encoded light beams.
 8. The method of claim 7, wherein each of the respective in-coupling gratings is rotated around an optical axis relative to the spatial light modulator.
 9. The method of claim 7, wherein admitting each of the plurality of encoded light beams at the respective in-coupling grating of each light-guiding optical element of the plurality of light-guiding optical elements comprises encountering the respective in-coupling grating only once.
 10. The method of claim 4, wherein the plurality of sub-light sources are rotated around an optical axis relative to the spatial light modulator.
 11. The method of claim 4, further comprising modifying a shape of a pupil formed by each of the plurality of encoded light beams using a mask.
 12. The method of claim 11, wherein the mask is adjacent to the plurality of light-guiding optical elements.
 13. The method of claim 4, further comprising modifying a size of a pupil formed by each of the plurality of encoded light beams using an optical element, wherein the optical element is adjacent to the plurality of light-guiding optical elements.
 14. The method of claim 1, wherein each beam of the plurality of light beams differs from other beams of the plurality of light beams in at least one light property.
 15. The method of claim 14, wherein the at least one light property comprises color.
 16. The method of claim 14, wherein the at least one light property comprises polarization.
 17. The method of claim 1, wherein each of the plurality of sub-light sources are spatially separated from each other.
 18. The method of claim 17, wherein the plurality of sub-light sources comprises a first group of sub-light sources and a second groups of sub-light sources, and wherein sub-light sources of the first group are displaced from sub-light sources of the second group along an optical path of the imaging system.
 19. The method of claim 1, further comprising increasing a numerical aperture of the plurality of sub-light sources using a pupil expander.
 20. The method of claim 19, wherein the pupil expander comprises a film having a prism pattern disposed thereon. 